Factorise id3v2 header parsing from mp3.c to be shared

Patch by Alex Converse ( alex converse gmail com )

Originally committed as revision 16615 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/Makefile

@@ -93,7 +93,7 @@ OBJS-$(CONFIG_MMF_MUXER)                 += mmf.o riff.o
 OBJS-$(CONFIG_MOV_DEMUXER)               += mov.o riff.o isom.o
 OBJS-$(CONFIG_MOV_MUXER)                 += movenc.o riff.o isom.o avc.o
 OBJS-$(CONFIG_MP2_MUXER)                 += mp3.o
-OBJS-$(CONFIG_MP3_DEMUXER)               += mp3.o
+OBJS-$(CONFIG_MP3_DEMUXER)               += mp3.o id3v2.o
 OBJS-$(CONFIG_MP3_MUXER)                 += mp3.o
 OBJS-$(CONFIG_MP4_MUXER)                 += movenc.o riff.o isom.o avc.o
 OBJS-$(CONFIG_MPC_DEMUXER)               += mpc.o

libavformat/id3v2.c

@@ -0,0 +1,35 @@
+/*
+ * ID3v2 header parser
+ * Copyright (c) 2003 Fabrice Bellard
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include "id3v2.h"
+
+int ff_id3v2_match(const uint8_t *buf)
+{
+    return  buf[0] == 'I' &&
+            buf[1] == 'D' &&
+            buf[2] == '3' &&
+            buf[3] != 0xff &&
+            buf[4] != 0xff &&
+            (buf[6] & 0x80) == 0 &&
+            (buf[7] & 0x80) == 0 &&
+            (buf[8] & 0x80) == 0 &&
+            (buf[9] & 0x80) == 0;
+}

libavformat/id3v2.h

@@ -0,0 +1,35 @@
+/*
+ * ID3v2 header parser
+ * Copyright (c) 2003 Fabrice Bellard
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#ifndef AVFORMAT_ID3V2_H
+#define AVFORMAT_ID3V2_H
+
+#include <stdint.h>
+
+#define ID3v2_HEADER_SIZE 10
+
+/**
+ * Detects ID3v2 Header.
+ * @buf must be ID3v2_HEADER_SIZE byte long
+ */
+int ff_id3v2_match(const uint8_t *buf);
+
+#endif /* AVFORMAT_ID3V2_H */

libavformat/mp3.c

@@ -24,8 +24,8 @@
 #include "libavcodec/mpegaudio.h"
 #include "libavcodec/mpegaudiodecheader.h"
 #include "avformat.h"
+#include "id3v2.h"
 
-#define ID3v2_HEADER_SIZE 10
 #define ID3v1_TAG_SIZE 128
 
 #define ID3v1_GENRE_MAX 125
@@ -159,20 +159,6 @@ static const char * const id3v1_genre_str[ID3v1_GENRE_MAX + 1] = {
     [125] = "Dance Hall",
 };
 
-/* buf must be ID3v2_HEADER_SIZE byte long */
-static int id3v2_match(const uint8_t *buf)
-{
-    return  buf[0] == 'I' &&
-            buf[1] == 'D' &&
-            buf[2] == '3' &&
-            buf[3] != 0xff &&
-            buf[4] != 0xff &&
-            (buf[6] & 0x80) == 0 &&
-            (buf[7] & 0x80) == 0 &&
-            (buf[8] & 0x80) == 0 &&
-            (buf[9] & 0x80) == 0;
-}
-
 static unsigned int id3v2_get_size(ByteIOContext *s, int len)
 {
     int v=0;
@@ -371,7 +357,7 @@ static int mp3_read_probe(AVProbeData *p)
     uint8_t *buf, *buf2, *end;
     AVCodecContext avctx;
 
-    if(id3v2_match(p->buf))
+    if(ff_id3v2_match(p->buf))
         return AVPROBE_SCORE_MAX/2+1; // this must be less than mpeg-ps because some retards put id3v2 tags before mpeg-ps files
 
     max_frames = 0;
@@ -487,7 +473,7 @@ static int mp3_read_header(AVFormatContext *s,
     ret = get_buffer(s->pb, buf, ID3v2_HEADER_SIZE);
     if (ret != ID3v2_HEADER_SIZE)
         return -1;
-    if (id3v2_match(buf)) {
+    if (ff_id3v2_match(buf)) {
         /* parse ID3v2 header */
         len = ((buf[6] & 0x7f) << 21) |
             ((buf[7] & 0x7f) << 14) |